// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Utility class that performs basic operations on header value tokens: parsing
// them out, checking for presense of certain tokens, and removing them.

#ifndef NET_TOOLS_BALSA_BALSA_HEADERS_TOKEN_UTILS_H_
#define NET_TOOLS_BALSA_BALSA_HEADERS_TOKEN_UTILS_H_

#include "base/strings/string_piece.h"
#include "net/tools/balsa/balsa_headers.h"

namespace net {

class BalsaHeadersTokenUtils {
public:
    // All the functions below respect multiple header lines with the same key.

    // Checks whether the last header token matches a given value. Useful to
    // check the outer-most content or transfer-encoding, for example. In the
    // presence of multiple header lines with given key, the last token of the
    // last line is compared.
    static bool CheckHeaderForLastToken(const BalsaHeaders& headers,
        const base::StringPiece& key,
        const base::StringPiece& token);

    // Tokenizes header value for a given key. In the presence of multiple lines
    // with that key, all of them will be tokenized and tokens will be added to
    // the list in the order in which they are encountered.
    static void TokenizeHeaderValue(const BalsaHeaders& headers,
        const base::StringPiece& key,
        BalsaHeaders::HeaderTokenList* tokens);

    // Removes the last token from the header value. In the presence of multiple
    // header lines with given key, will remove the last token of the last line.
    // Can be useful if the last encoding has to be removed.
    static void RemoveLastTokenFromHeaderValue(const base::StringPiece& key,
        BalsaHeaders* headers);

    // Given a pointer to the beginning and the end of the header value
    // in some buffer, populates tokens list with beginning and end indices
    // of all tokens present in the value string.
    static void ParseTokenList(const char* start,
        const char* end,
        BalsaHeaders::HeaderTokenList* tokens);

private:
    // Helper function to tokenize a header line once we have its description.
    static void TokenizeHeaderLine(
        const BalsaHeaders& headers,
        const BalsaHeaders::HeaderLineDescription& line,
        BalsaHeaders::HeaderTokenList* tokens);

    BalsaHeadersTokenUtils(); // Prohibit instantiation
};

} // namespace net

#endif // NET_TOOLS_BALSA_BALSA_HEADERS_TOKEN_UTILS_H_
